U.S. patent application number 10/150621 was filed with the patent office on 2003-11-20 for transmyocardial implant with natural vessel graft and method.
This patent application is currently assigned to HeartStent Corporation. Invention is credited to Schollmeyer, Michael, Tweden, Katherine S..
Application Number | 20030216801 10/150621 |
Document ID | / |
Family ID | 29419291 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030216801 |
Kind Code |
A1 |
Tweden, Katherine S. ; et
al. |
November 20, 2003 |
Transmyocardial implant with natural vessel graft and method
Abstract
A transmyocardial implant includes a hollow rigid conduit having
a vessel portion and a myocardial portion. The vessel portion is
sized to be inserted into a blood vessel segment taken from a
non-coronary artery or vein. The myocardial portion is sized to
extend from the vessel portion and through a myocardium into a
heart chamber. The conduit has open vessel and myocardial ends on
respective ends of the vessel and myocardial portions to define a
blood flow pathway within an interior of the conduit between the
vessel and myocardial ends. The myocardial portion is formed of a
conduit material sufficiently rigid to resist deformation and
closure of the pathway in response to contraction of the
myocardium. The vessel portion has a radial compliance
approximating a radial compliance of the vessel.
Inventors: |
Tweden, Katherine S.;
(Mahtomedi, MN) ; Schollmeyer, Michael; (Maple
Grove, MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
HeartStent Corporation
|
Family ID: |
29419291 |
Appl. No.: |
10/150621 |
Filed: |
May 17, 2002 |
Current U.S.
Class: |
623/1.13 |
Current CPC
Class: |
A61F 2220/0008 20130101;
A61F 2220/0075 20130101; A61F 2/94 20130101; A61F 2/2493
20130101 |
Class at
Publication: |
623/1.13 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. A method revascularizing a coronary vessel of a patient
comprising: inserting a hollow conduit through a heart wall so that
a first end of the conduit extends into a heart chamber and a
second end of the conduit extends beyond the heart wall; connecting
the second end of the conduit with a first end of a natural vessel
graft wherein the first end of the natural vessel graft is outside
the heart wall; and attaching a second end of the natural vessel
graft to the coronary artery.
2. The method of claim 1, wherein the coronary vessel includes an
occlusion which at least partially blocks a flow of blood within
the coronary distal the occlusion, the connection between the
natural vessel graft and the coronary vessel is distal the
occlusion and a blood flow from the second end of the natural
vessel graft into the coronary vessel is directed away from the
occlusion.
3. The method of claim 1, wherein a stent is attached to the second
end of the conduit and the natural vessel graft is attached to the
stent.
4. The method of claim 1 wherein the coronary vessel is a coronary
artery.
5. The method of claim 1, wherein the heart chamber is a left
ventricle.
6. The method of claim 1, wherein the natural vessel graft is from
a non-coronary vessel within the patient.
7. The method of claim 6, wherein the natural vessel graft is
selected from one of an internal mammary artery, a lesser saphenous
vein, a gastroepiploic artery, an inferior epigastric artery, and
an arm artery.
8. The method of claim 2, wherein the conduit is inserted through
the heart wall within the coronary vessel.
9. The method of claim 2, wherein the coronary vessel is incised
distal the occlusion forming a first end adjacent to the occlusion
and a second end, the first end of the coronary vessel being closed
and the second end of the natural vessel graft is attached to the
second end of the coronary vessel with an end to end
anastomosis.
10. The method of claim 2, wherein the conduit is inserted through
the heart wall offset from the coronary vessel and the second end
of the natural vessel graft attached to the coronary vessel with an
end to side anastomosis.
11. The method of claim 10, wherein the end to side anastomosis is
at an angle with respect to an axis of flow of the coronary
vessel.
12. The method of claim 11, wherein the angle is oriented to direct
blood flow from the second end of the vessel graft in the direction
of blood flow in the coronary vessel.
13. An implant for revascularizing a coronary vessel comprising: a
hollow conduit with a first portion with a first end and a second
portion with a second end, the first portion adapted to be
positioned with a myocardium and extend into a heart chamber, the
second portion extending outside the myocardium; a stent attached
to the second end of the hollow conduit; a natural vessel graft
with a first end attached to the stent so that no portion of the
natural vessel graft is within the myocardium when the first
portion of the conduit is placed with the myocardium, and a second
end adapted to be attached to the coronary vessel; wherein the
implant is adapted to provide fluid communication between the heart
chamber and the coronary vessel when the first portion is placed
within the myocardium extending into the heart chamber and the
second end of natural vessel graft is attached to the coronary
vessel.
14. The implant of claim 13, wherein the coronary vessel is a
coronary artery.
15. The implant of claim 13, wherein the heart chamber is a left
ventricle.
16. The implant of claim 14, wherein the natural vessel graft is
from a non-coronary vessel.
17. The implant of claim 16, wherein the natural vessel graft is
selected from one of an internal mammary artery, a lesser saphenous
vein, a gastroepiploic artery, an inferior epigastric artery, and
an arm artery.
18. The implant of claim 13, wherein the second end of the natural
vessel graft is attached to the coronary vessel by an end to side
anastomosis.
19. The implant of claim 13, wherein the second end of the natural
vessel graft is attached to the coronary vessel by an end to end
anastomosis.
20. The implant of claim 19, wherein the end to side anastomosis is
at an angle with respect to an axis of flow of the coronary
vessel.
21. The implant of claim 20, wherein the angle is oriented to
direct blood flow from the second end of the vessel graft in the
direction of blood flow in the coronary vessel.
Description
FIELD OF THE INVENTION
[0001] This invention pertains to an implant for passing blood flow
directly between a chamber of the heart and a coronary vessel. More
particularly, this invention pertains to a transmyocardial implant
with a non-coronary blood vessel attached to the implant.
BACKGROUND OF THE INVENTION
[0002] Coronary artery disease is the leading cause of premature
death in industrialized societies. The mortality statistics tell
only a portion of the story. Many who survive face prolonged
suffering and disability.
[0003] Arteriosclerosis is "a group of diseases characterized by
thickening and loss of elasticity of arterial walls." DORLAND'S
ILLUSTRATED MEDICAL DICTIONARY 137 (27th ed. 1988).
Arteriosclerosis "comprises three distinct forms: atherosclerosis,
Monckeberg's arteriosclerosis, and arteriolosclerosis." Id.
[0004] Coronary artery disease has been treated by a number of
means. Early in this century, the treatment for arteriosclerotic
heart disease was largely limited to medical measures of
symptomatic control. Evolving methods of diagnosis, coupled with
improving techniques of post-operative support, now allow the
precise localization of the blocked site or sites and either their
surgical re-opening or bypass.
[0005] The traditional open-chest procedure for coronary artery
bypass grafting requires an incision of the skin anteriorly from
nearly the neck to the navel, the sawing of the sternum in half
longitudinally, and the spreading of the ribcage with a mechanical
device to afford prolonged exposure of the heart cavity. If the
heart chamber or a vessel is opened, a heart-lung, or
cardiopulmonary bypass, procedure is usually necessary.
[0006] Depending upon the degree and number of coronary vessel
occlusions, a single, double, triple, or even greater number of
bypass procedures may be necessary. Often each bypass is
accomplished by the surgical formation of a separate conduit from
the aorta to the stenosed or obstructed coronary artery at a
location distal to the diseased site.
[0007] The major obstacles to coronary artery bypass grafting
include both the limited number of vessels that are available to
serve as conduits and the skill required to effect complicated
multiple vessel repair. Potential conduits include the two
saphenous veins of the lower extremities, the two internal thoracic
(mammary) arteries under the sternum, and the single gastroepiploic
artery in the upper abdomen.
[0008] Newer procedures using a single vessel to bypass multiple
sites have evolved. This technique has its own inherent hazards.
When a single vessel is used to perform multiple bypasses, physical
stress(e.g.,torsion) on the conduit vessel can result. Such torsion
is particularly detrimental when this vessel is an artery.
Unfortunately, attempts at using artificial vessels or vessels from
other species (xenografts), or other non-related humans
(homografts) have been largely unsuccessful. See LUDWIG K. VON
SEGESSER, ARTERIAL GRAFTING FOR MYOCARDIAL REVASCULARIZATION:
INDICATIONS, SURGICAL TECHNIQUES AND RESULTS 38-39 (1990)
[0009] While experimental procedures transplanting alternative
vessels continue to be performed, in general clinical practice,
there are five vessels available to use in this procedure over the
life of a particular patient. Once these vessels have been
sacrificed or affected by disease, there is little or nothing that
modern medicine can offer. It is unquestionable that new methods,
not limited by the availability of such conduit vessels, are
needed.
[0010] Direct revascularization devices (DRDs) provide an
alternative to traditional vein graft bypass operations
incorporating harvested vessels. DRDs permit the revascularization
of coronary vessels by placement of an artificial conduit between a
heart chamber and the coronary vessel, allowing blood flow directly
from the heart chamber into a lumen of the vessel. DRDs and methods
for implanting such devices are described in U.S. Pat. No.
5,944,019.
[0011] DRDs incorporating conduit portions with different degrees
of radial compliance are described in currently pending and
commonly assigned U.S. patent application Ser. No. 09/304,650.
Utilization of varying degrees of radial compliance allows the
conduit to have sufficient rigidity within the muscle of the heart
wall to prevent collapse while having flexibility more closely
matching that of the target vessel.
[0012] Further, U.S. Pat. No. 6,250,305 describes the incorporation
of natural vessel grafts with artificial conduit DRDs to perform
revascularization. The techniques described in the '305 patent
allow the connection to the target vessel to be made using a
natural vessel graft. While this is a distinct improvement to prior
art of vein graft bypass procedures described above, the issue of
only having a limited number of suitable vessel for natural graft
bypass remains. An approach permitting direct revascularization of
coronary vessels incorporating the advantages of artificial conduit
DRDs with the advantages of natural vessel grafts is desirable.
SUMMARY OF THE INVENTION
[0013] The present invention relates to an implant for establishing
a blood flow path between a heart chamber and a coronary vessel
through the myocardium. The implant includes a hollow conduit
having a vessel portion and a myocardial portion. The myocardial
portion is sized to extend from the vessel portion and through the
myocardium to the heart chamber. The myocardial portion is
preferably formed of a conduit material sufficiently rigid to
resist deformation and closure of the pathway in response to
contraction of the myocardium. The vessel portion extends outside
the heart wall. In certain embodiments, the vessel portion can have
an open structure such as a mesh. In one embodiment, the vessel
portion is connected to the coronary vessel by using a relatively
short natural graft section that is secured to the open mesh and is
also secured to the coronary vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a side perspective view of a prior art
transmyocardial conduit for use with the present invention.
[0015] FIG. 2 is a side perspective view of a prior art stent for
use with a transmyocardial conduit for use with the present
invention, shown elongated to define a smaller diameter.
[0016] FIG. 3 is a side perspective view of the prior art stent of
FIG. 2, shown shortened to define a larger diameter.
[0017] FIG. 4 is a side cross-sectional view of the prior art
transmyocardial conduit of FIG. 1 with the stent of FIGS. 2 and 3
mounted about a vessel end.
[0018] FIG. 5 is a cross-sectional view of an occluded coronary
vessel on a heart wall.
[0019] FIG. 6 is a cross-sectional view of the coronary vessel of
FIG. 5 with the vessel incised and legated distal the
occlusion.
[0020] FIG. 7 is a cross-sectional view of the coronary vessel of
FIG. 6 with the transmyocardial conduit of FIG. 4 extending through
the myocardium.
[0021] FIG. 8 is a cross-sectional view of the coronary vessel of
FIG. 7 with the transmyocardial conduit connecting a heart chamber
with a lumen of the coronary vessel.
[0022] FIG. 9 is a perspective view of a second embodiment of a
transmyocardial conduit connecting a heart chamber to a lumen of a
coronary vessel without a stent about the conduit.
[0023] FIG. 10 is a partial cross-sectional view of a third
embodiment of a transmyocardial conduit according to the present
invention connecting a heart chamber with a lumen of a coronary
vessel including a tissue-growth promoting material about the
myocardial portion of the conduit.
[0024] FIG. 11 is a side perspective view of a portion of a heart
wall with a fourth embodiment of a transmyocardial conduit
connecting a heart chamber with a lumen of a coronary vessel via an
end-to-side anastomosis.
[0025] FIG. 12 is a side perspective view of a portion of a heart
wall with a fifth embodiment of a transmyocardial conduit
connecting a heart chamber with a lumen of a coronary vessel via an
end-to-side anastomosis with the conduit at a non-perpendicular
angle to the vessel.
DETAILED DESCRIPTION
[0026] With initial reference to FIGS. 1 through 4, a prior art
transmyocardial conduit 10 is shown in the form of an L-shaped
rigid tube. In this embodiment, conduit 10 is made of titanium but
may be made of any other rigid biocompatible material such as
pyrolytic carbon or may be titanium coated with pyrolytic carbon.
The material of the conduit 10 is preferably sufficiently rigid to
withstand contraction forces of the myocardium. By way of example,
conduit 10 will have an outside diameter in the range of about 1 to
4 millimeters and a wall thickness of about 0.25 millimeters.
[0027] Conduit 10 has a vessel portion 12 including a first open
end 16 into an interior 19. Conduit 10 has a myocardial portion 14
extending at an angle to the axis of portion 12 and including a
second open end 18. Myocardial portion 14 is sized to extend
through the myocardium 84 (as shown in FIG. 7) so that vessel
portion 12 is at or near an outer wall of myocardium 84 and open
end 18 of myocardial portion 14 protrudes into a heart chamber 86
of a patient's heart.
[0028] Conduit 10 may include a stent 20 (shown in FIGS. 2, 3 and
4) which may be a tubular member of lattice formed of biocompatible
material. When elongated, stent 20 has an initial diameter D.sub.1
(shown in FIG. 2) which is larger than a conduit outer diameter
D.sub.0 (shown in FIG. 1) and further sized for stent 20 to be
inserted into lumen 80 of the vessel to be used as a connector.
When shortened, stent 20 is expandable to an enlarged diameter
D.sub.2 (shown in FIG. 3). It will be appreciated that coronary
stents such as stent 20 are commercially available in a wide
variety of sizes, shapes, materials and mode of expansion (e.g.,
self-expanding or balloon expandable). Stent 20 can be any member
whose outside dimensions expand to fit within a lumen 80 of a
coronary vessel 82 (see FIG. 5) and whose internal dimensions
permit insertion of vessel portion 12 within stent 20. Conduit 10
and stent 20 are described in further detail in U.S. Pat. No.
6,053,942, the disclosure of which is incorporated herein by
reference.
[0029] Referring now to FIGS. 5 through 8, use of a first
embodiment of a transmyocardial conduit 10 to revascularize a
coronary vessel 82 with an occlusion 87 is shown. Vessel 82 lies on
an outer surface of myocardium 84. Occlusion 87 prevents adequate
flow of blood to vessel 82 distal to occlusion 87, as shown in FIG.
5. To provide adequate blood flow distal to occlusion 87, vessel 82
is legated distal to an obstruction 87 with sutures 85. An incision
is made through the vessel 82 distal to the legating suture 85, as
shown in FIG. 6, defining a first distal incised end 82a.
[0030] A portion of vessel 82 is dissecting at first incised end
82a to define a second distal incised end 82b. The segment of
vessel removed between first incised end 82a and second incised end
82b may be used to form a graft 30 having ends 31 and 32 (see FIG.
7). Alternatively, as discussed below, another source may be
available to provide graft 30. For example, in another embodiment,
graft 30 is a natural vein segment harvested form within the body
of the patient for whom the coronary vessel revascularization is
being performed. In a gap defined between occlusion 87 and incised
end 82a, a blood flow pathway is formed through myocardium 84 to
allow fluid communication with a heart chamber 86. Conduit 10 is
placed within the blood flow pathway with myocardial portion 14
extending the myocardium 84 into heart chamber 86, as shown in FIG.
7. Vessel portion 12 of conduit 10 lies along an exterior surface
of myocardium 84. Fixed about an end of vessel portion 12 opposite
myocardial portion 14 is stent 20.
[0031] In FIG. 8, end 31 of graft 30 is positioned about stent 20
and secured by sutures 83 to stent 20. End 32 of graft 30 has been
attached to vessel 82 and allows fluid communication between heart
chamber 86 and lumen 80 via an interior 19 of conduit 10. The
connection between graft 30 and vessel 82 is an end-to-end
anastomosis 91.
[0032] Referring now to FIG. 9, a second embodiment of the present
invention is shown. This embodiment is similar to the first
embodiment described above with reference to FIGS. 5 through 8. In
the second embodiment, graft 30 is connected directly to vessel end
12 of conduit 10 without stent 20 interposed between and is secured
to conduit 10 with sutures 83. All other elements of the first
embodiment are included in the second embodiment.
[0033] Referring now to FIG. 10, a third embodiment of a
transmyocardial conduit for revascularizing a coronary vessel is
shown. This embodiment is similar to the first embodiment detailed
above with the additional of a sleeve 15 made of a tissue-growth
inducing material such as polyester about myocardial portion 14.
The use of such sleeves about myocardial implants to anchor the
implants within the myocardium is discussed in further detail in
U.S. Pat. No. 5,984,956, the disclosure of which is incorporated
herein by reference.
[0034] In place of stent 20, conduit 10 in FIG. 10 includes a
compliant sleeve 120 about which is mounted graft 30. Complaint
sleeve 120 has a degree of radial compliance which is adapted to
match the radial compliance of graft 30. Further description of the
use of sleeve 120 with radial compliance matched to the compliance
of the vessel into which the sleeve extends is found in
commonly-assigned pending U.S. patent application Ser. No.
09/304,650, the disclosure of which is incorporated herein by
reference.
[0035] Referring now to FIG. 11, a further embodiment of a
transmyocardial conduit for revascularizing a coronary vessel is
shown. In this embodiment, conduit 10, with or without stent 20,
provides fluid communication between heart chamber 86 and lumen 80
via graft 30 which is connected to vessel 82 with an end-to-side
anastomosis 90. This embodiment does not require vessel 82 to be
incised or dissected. However, since vessel 82 is not being incised
or dissected, an alternative source for graft 30 within the
patient's body will need to be found. Following a standard method
of coronary artery bypass surgery, a portion of a suitable blood
vessel such as the internal mammary artery may be available from
segments of the artery not required for the bypass procedure.
Alternatively, other vessels may be used as a source for graft 30,
such as the radial artery, the lesser saphenous vein, an arm vein,
the gastroepiploic artery, the inferior epigastric artery or other
vessels of suitable size.
[0036] Conduit 10 is placed by inserting second portion 14 through
myocardium 84 with open end 18 in communication with left ventricle
86. First portion 12 is inserted into enlarged stent 20 (See FIGS.
1, 5). An embodiment of a method of placing an implantable conduit
between a chamber of the heart and a coronary vessel is described
in detail in U.S. Pat. No. 5,755,682, the disclosure of which is
hereby incorporated by reference.
[0037] In one embodiment of the invention, following a standard
method of coronary artery bypass surgery, the surgeon may have a
portion 30 of a suitable blood vessel such as the internal mammary
artery. Depending on the availability of vessels and the technique
preferred by the surgeon other vessels may be used such as the
radial artery, the lesser saphenous vein, an arm vein, the
gastroepiploic artery or the inferior epigastric artery. Portion 30
has two ends 31, 32. The surgeon then takes portion 30 of this
residual vessel (for example, the internal mammary artery) and
slides end 31 over the stent 20. (See FIG. 5) Eend 32 of the
portion 30 is connected to end 82b of the ligated coronary artery
82 by methods well known to those with skill in the art. The
surgically connected structure consisting of the stent 20, the
piece of blood vessel 30 and the coronary artery 82 is then
stabilized on the myocardium 84.
[0038] This may be the preferred embodiment of the present
application in that it allows a more efficient and complete usage
of harvested vessels during bypass procedures. Using the present
invention in conjunction with standard vein graft bypass procedures
will permit multiple bypasses to be created with a single harvested
vessel by utilizing pieces of the native vessel that otherwise
would have been discarded. In this way, patients requiring
additional bypass procedures at a future date will still have
usable vessels for traditional bypass procedures. Alternatively,
for patients who have no remaining vessels suitable for traditional
bypass procedures, the present method offers an approach which
utilizes vessels not otherwise considered usable for bypass.
[0039] In another embodiment of the invention shown in FIG. 11,
conduit 10 is implanted by inserting second portion 14 through
myocardium 84 with open end 18 in communication with left ventricle
86. End 31 of portion 30 is attached to first portion 12 of conduit
10 either directly or utilizing a stent 20 depending on the
preference of the surgeon. End 32 is then anastomosed to the
selected coronary artery 82 via an end to side anastomosis 90.
[0040] FIG. 12 shows a similar embodiment to that shown in FIG. 11,
with the difference being that conduit 10 forms an end-to-side
anastomosis 90 with vessel 82 at an angle. The angle of anastomosis
90 is angled to bias flow out of conduit 10 in the direction of
normal blood flow within vessel 80.
[0041] From the foregoing, the invention has been described in a
preferred embodiment. Modifications and equivalents of the
disclosed concepts are intended to be included within the scope of
the claims.
* * * * *